Re: How to access the output samples of a multichannel mixer unit
Re: How to access the output samples of a multichannel mixer unit
- Subject: Re: How to access the output samples of a multichannel mixer unit
- From: Charlie Roberts <email@hidden>
- Date: Tue, 28 Jun 2011 16:07:28 -0700
Hi Brian, thanks for the response. The original poster specifically mentioned needing access to the output samples of the mixer, so that's why I assumed that there would be no direct connection of the mixer node. As you mentioned, you can't have a callback and connection at the same node. I didn't mean to imply there couldn't be connections of nodes at all in the graph, but in the brief use case he outlined it doesn't seem like there would be.
I'm curious about your statement "there are many useful Apple AudioUnits to choose from". There's VoiceProcessing, iPodEQ, Mixer, and the format converter. It's not in anyway similar to the OS X audiounit landscape.
Any type of longer signal processing chain proved difficult for me to realize coming to AUGraphs as a newbie. Have you done a graph similar to the following in iOS?
remoteIO (mic / line in) -> distortion -> chorus -> delay -> reverb -> remoteIO (output)
or
saw generator -> low-pass filter -> envelope generator -> reverb -> remoteIO (output)
If so, I think an overview of how you did it would be a really useful contribution to the community... definitely at least for me :) I'm not sure I follow what you mean by a T-connection in this context.
My other question would be: what's the advantage of using a graph for the original poster? Why not just:
1. create a remoteIO unit and a mixer unit
2. assign your callback functions that produce sound to the mixer unit
3. assign a callback to the remoteIO unit that tells the mixer unit to render and process the samples
Thanks in advance for any thoughts. - Charlie
On Tue, Jun 28, 2011 at 3:22 PM, Brian Willoughby
<email@hidden> wrote:
What makes you think that the nodes in an AUGraph would not actually be connected under iOS?
Granted, you cannot connect to custom AudioUnits, but there are many useful Apple AudioUnits to choose from, and I often find that I need them.
Also, if all you want is a single mixer, then, yes, all your inputs would be callbacks and your output would be a callback, so in effect it's as if there are no actual connections. But, if you create a graph that has more than one node then you certainly should have actual connections in your graph. In other words, assigning a callback only breaks the connection that you're specifying, but none of the other connections are affected.
Perhaps what you're noting is that you cannot have both a callback and a connection at the same node. You'd need some sort of T-connection for that. I guess we need more details about what you're trying to do and why you think AUGraph doesn't have actual connections, and then maybe we can get to the bottom of this.
Brian Willoughby
Sound Consulting
On Jun 28, 2011, at 12:37, Charlie Roberts wrote:
You could assign a callback to the input of remoteIO (or another mixer) that uses AURender to explicitly tell your mixer to render into a bufferlist. The nodes in the graph would not actually be connected, which sort of implies there's little point in using a graph in the first place.
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